Norm,
Could it be as simple as the user(s) not HAVING a C:\Windows\Temp? I don't have one on my NT developer's system, since the OS was installed in WINNT. We employ a wrapper EXE on the network drive that looks for a specific C folder, and creates it if it isn't found. The EXE is then copied there if it is missing on C or if the network version is newer.

Barbara